1. Field of the Invention
The present invention relates to an information record medium such as an optical disk of a high recording density type, which is capable of recording information such as video information, audio information and the like at a high density, and which is represented by a DVD (Digital Video or Versatile Disk). The present invention also relates to a recording apparatus for recording the information onto the information record medium, and a reproducing apparatus for reproducing the information from the information record medium.
2. Description of the Related Art
Recently, as a data compressing technique to effectively utilize the memory capacity of an information record disk such as an optical disk for recording video information and the like, a variable rate system such as the MPEG 2 (Moving Picture Experts Group 2) method and the like is proposed. In general, in case of reducing the information amount by use of the compressing technique, the information amount after compression is not constant due to the property of the original signal and the like. This variable rate system is not a system which compress the information at a constant rate in case of recording the information after compression onto the record medium, but is a system which records the information after compression onto the record medium while compressing the information by a data or information compression rate, which is set as a rate appropriate and variable from scene to scene, by use of mutual relationships between the units of data or information successively recorded and reproduced, such as the units of video data related to one scene and the like.
In order to reproduce the data or information, which is recorded by this type of variable rate system and which information amount required for the reproduction (per unit time) is changed, from the record medium, there may be proposed two methods as following.
As a first method, there is a method of changing a linear velocity at a read position of an optical pickup for reading out the information in the reproducing apparatus with respect to a record portion of the information record disk (hereinbelow, it is referred to as a xe2x80x9creading linear velocityxe2x80x9d) at the time of reproducing the information, in accordance with the information amount after compression of the information record disk. The time change of the information amount after compression, which is read out per unit time at the time of reproducing the record information (hereinbelow, it is referred to as an xe2x80x9cinformation ratexe2x80x9d), and the time change of the rotation number of the disk i.e. the reading linear velocity at the time of reproduction according to this first method are shown in FIG. 17. As shown in FIG. 17, according to this first method, the data reading rate i.e. the reading linear velocity (or the rotation number) is changed in accordance with the information rate from time to time so as to always obtain the information rate required for the reproduction by the reproducing apparatus. In FIG. 17, the difference between the information rate, which is actually reproduced in accordance with the reading linear velocity (indicated by a dashed line), and the information rate of the record information after compression (indicated by a solid line), is corresponding to a loss at the time of reproduction due to various factors such as a reproduction of additional information and the like. As a result, since the data amount obtained through the optical pickup and the data amount required for the reproduction are almost coincident to each other, it is possible to reduce the size (i.e. the memory capacity) of a track buffer of the reproducing apparatus. Further, it is possible to restrain the consumption of the electric power, since the rotation number of the spindle motor for rotating the disk can be reduced to be a level of minimum requirement. Furthermore, a special control, such as a switching control for switching the stand by or waiting condition and the reproducing condition of the optical pickup and the like, is not necessary.
As a second method, there is a method of setting the data reading rate i.e. the reading linear velocity to match the upper limit of the information rate required for the reproduction (i.e., so as to be able to reproduce even in case of the upper limit) as shown in FIG. 18, and rotating the spindle motor at a speed to make this data reading rate constant. As a result, the frequency of the read out clock is made constant, so that it is enough to prepare just one PLL (Phase Lock Loop) circuit of normal type for the demodulation of the data.
However, according to the aforementioned first method, since the frequency of the read out clock is always changed, a special PLL circuit is required for the demodulation, the control of such a special circuit becomes complicated, and the rotation control of the spindle motor becomes also complicated, resulting in that this first method is not practical.
On the other hand, according to the aforementioned second method, since the data amount used for the demodulation is greatly changed, it is necessary for the optical pickup to repeat the reproducing condition, in which the optical pickup successively read out the information, and the stand by condition, in which the optical pickup is standing by on a same track, so that the control of the optical pickup becomes complicated. Further, since the difference between the data amount read out from the optical pickup and the data required for the demodulation is so large that it is necessary to install the reproducing apparatus with a track buffer of large size (i.e. large memory capacity). Furthermore, since the motor is always rotating in accordance with the highest speed, the power consumption is also increased. Therefore, especially in case of a portable player, the life of the buttery is shortened, resulting in that the convenience in usage is certainly degraded.
On the other hand, a proposal and a development are being made as for the DVD, as an optical disk in which the memory capacity is improved by about ten times without changing the size of the optical disk itself as compared with the aforementioned conventional CD. As for the DVD, it is expected that the information can be compressed and recorded by the aforementioned variable rate system. However, there is no proposal or development made as for a DVD technique to solve the problems owned by the aforementioned first and second methods. Further, in the technical art of the DVD, the actuality is such that a person having an ordinary skill in this art does not even recognize the problem or subject itself which happens at the time of applying the compression technique, such as the variable rate system, with respect to the DVD, which has the large memory capacity.
It is therefore an object of the present invention to provide an information record medium, which can be easily reproduced at various information rates, an apparatus for recording the information record medium, and an apparatus for reproducing the information record medium by use of a relatively simple construction.
The above object of the present invention can be achieved by an information record medium having a record track recorded with record information to be reproduced by an information reproducing apparatus. The information reproducing apparatus has a read device, and performs a reproduction while moving the read device along the record track at a predetermined reading linear velocity. The record information divided into a plurality of first data groups, each of which is a unit able to be accessed by the information reproducing apparatus, is recorded on the record track. Lowest reading rate information indicating a minimum requirement of a reading rate for the information reproducing apparatus to reproduce a reproduction unit, which comprises at least one of the first data groups and which is to be reproduced by the information reproducing apparatus such that a sequential logical meaning of the reproduction unit is continuous, is recorded on the record track at one portion different from another portion where the record information is recorded.
According to the information record medium of the present invention, the record information, such as video information, audio information and the like, is divided into a plurality of first data groups, and is recorded on the record track. Here, each of the first data groups is a unit able to be accessed in a logical meaning or physical meaning corresponding to the content of the record information, in the reproducing operation by use of the read device, such as an optical pickup, by the information reproducing apparatus. And that, the lowest reading rate information is recorded on the record track at one portion different from another portion where the record information is recorded. The lowest reading rate information indicates the minimum requirement of the reading rate for the information reproducing apparatus to reproduce the reproduction unit. This reproduction unit comprises at least one of the first data groups and is to be reproduced by the information reproducing apparatus such that a sequential logical meaning of the reproduction unit is continuous. Here, the meaning of xe2x80x9ca sequential logical meaning of the reproduction unit is continuousxe2x80x9d is that the logical meaning, which the content of the record information has, is continuous, in general. For example, if the record information is the video information, the meaning is that the display obtained by reproducing this video information is continuous. If the record information is the audio information, the meaning is that the audio sound output obtained by reproducing this audio information is continuous. On the other hand, the xe2x80x9clowest reading rate informationxe2x80x9d may be information directly indicating the reading rate, or may be information indicating the reading linear velocity corresponding to this reading rate i.e. the information indirectly indicating the lowest reading rate. Therefore, by reproducing the lowest reading rate information in advance of reproducing the record information, such as the video information, the audio information and the like, and by reproducing the record information at a reading linear velocity not less than a reading linear velocity able to obtain the minimum requirement of the reading rate indicated by the reproduced lowest reading rate information, it is possible to perform the reproducing operation satisfactorily while restraining the electric power consumption to be a relatively low level by restraining the operation amount of the reproducing apparatus such as the rotation of the spindle motor and the like, by the reproducing apparatus.
In one aspect of the information record medium of the present invention, at least one portion of the record information is compressed by a variable information rate and is recorded on the record track.
According to this aspect, although at least one portion of the record information is compressed by the variable information rate by means of the MPEG 2 method or the like, since the reproducing apparatus can use the reading linear velocity based on the lowest reading rate information, the reproducing operation can be performed while restraining the electric power consumption to be a relatively low level by use of a relatively simple construction, by the reproducing apparatus.
In another aspect of the information record medium of the present invention, the lowest reading rate information indicates one of a first reading rate and a second reading rate which is equal to the first reading rate multiplied by xc2xdn (n: natural number).
According to this aspect, since it is enough for the reproducing apparatus to perform the demodulation of the record information in accordance with the reading rate equal to the first reading rate multiplied by xc2xdn (n=1, 2, 3, . . . ), by employing a relatively simple construction i.e. the known frequency divider for merely frequency-dividing one frequency signal to xc2xd times, xc2xc times, . . . , as the PLL for the demodulation, the reproduction which is harmonized with the information rate and which electric power consumption is low can be performed.
In another aspect of the information record medium of the present invention, the reproduction unit is a whole of the information record medium, and the lowest reading rate information is recorded at a lead in area of the information record medium.
According to this aspect, by firstly reproducing the lead in area and determining the reading linear velocity on the basis of the reproduced lowest reading rate information, the reproduction of the whole of the information record medium can be easily performed by use of this determined reading linear velocity.
In another aspect of the information record medium of the present invention, the reproduction unit comprises a plurality of second data groups, each of which is a unit able to be logically divided in the reproduction by the information reproducing apparatus and comprises sequential first data groups arranged along the record track among the first data groups. The lowest reading rate information is recorded at a predetermined portion on the record track for each of the second data groups.
According to this aspect, in case of reproducing each of the second data groups, by firstly reproducing the lowest reading rate information corresponding to respective one of the second data groups, and determining the reading linear velocity for each of the second data groups on the basis of this reproduced lowest reading rate information, the reproduction of each of the second data groups can be easily performed by use of this determined reading linear velocity. Therefore, in a case where the lowest reading rates are considerably different from each other between the second data groups, by employing the reading linear velocity suitable for each of the second data groups, the electric power consumption can be restrained to be a low level as a whole.
In another aspect of the information record medium of the present invention, the record information comprises at least one of video information and audio information. Each of the first data groups comprises the at least one information and control information including access information, which is information to access the at least one information.
According to this aspect, it is possible to easily access the video information, the audio information or the like for each first data group, on the basis of the access information by the reproducing apparatus.
The above object of the present invention can be also achieved by an information recording apparatus for recording record information onto an information record medium having a record track recorded with the record information to be reproduced by an information reproducing apparatus, which has a read device, and performs a reproduction while moving the read device along the record track at a predetermined reading linear velocity. The information recording apparatus is provided with: a record device for recording the record information divided into a plurality of first data groups, each of which is a unit able to be accessed by the information reproducing apparatus, onto the record track, and for recording lowest reading rate information indicating a minimum requirement of a reading rate for the information reproducing apparatus to reproduce a reproduction unit, which comprises at least one of the first data groups and which is to be reproduced by the information reproducing apparatus such that a sequential logical meaning of the reproduction unit is continuous, onto the record track at one portion different from another portion where the record information is recorded; and an input device for inputting the lowest reading rate information.
According to the information recording apparatus of the present invention, the record information such as the video information, the audio information and the like, are recorded on the record track by the record device. Here, when the lowest reading rate information indicating the minimum requirement of the reading rate is inputted by the input device, it is recorded on the record track at the predetermined portion by the record device. Therefore, it is possible to record the aforementioned information record medium of the present invention.
In one aspect of the information recording apparatus of the present invention, the record device records the lowest reading rate information indicating one of a first reading rate and a second reading rate which is equal to the first reading rate multiplied by xc2xdn (n: natural number).
According to this aspect, since the lowest reading rate information, indicating one of the first and second reading rates, is recorded by the record device, it is possible to record the aforementioned information record medium of the present invention.
In another aspect of the information recording apparatus of the present invention, the record information comprises at least one of video information and audio information, each of the first data groups comprises the at least one information and control information including access information, which is information to access the at least one information. The information recording apparatus is further provided with an access information generation device for generating the access information in association with the at least one information.
According to this aspect, since the access information to access the video information and/or the audio information is generated in association with these informations, by the access information generation device, and since the video information, the audio information and the control information including this access information are recorded by the record device, it is possible to record the aforementioned information record medium of the present invention.
The above object of the present invention can be also achieved by an information reproducing apparatus for reproducing an information record medium. In the information record medium, record information divided into a plurality of first data groups, each of which is a unit able to be accessed is recorded on a record track thereof, and in which lowest reading rate information indicating a minimum requirement of a reading rate to reproduce a reproduction unit, which comprises at least one of the first data groups and which is to be reproduced such that a sequential logical meaning of the reproduction unit is continuous, is recorded on the record track at one portion different from another portion where the record information is recorded. The information reproducing apparatus is provided with: a read device for reading information recorded at a predetermined read position on the record track; a drive device for moving the information record medium along the record track with respect to the read device; a reproduction device for reproducing the information read by the read device; and a controlling device for controlling the read device, the drive device and the reproduction device to reproduce the lowest reading rate information in advance of reading the record information by the read device, and to reproduce the record information by reading the record information at a reading linear velocity not less than a reading linear velocity able to obtain the minimum requirement of the reading rate indicated by the reproduced lowest reading rate information.
According to the information reproducing apparatus of the present invention, the information record medium is moved in a direction along the record track with respect to the read device by the drive device. The information recorded at the predetermined read position on the record track is read by the read device. The information read by the read device is reproduced by the reproduction device. Here, under the control of the control device, in advance of reading the record information such as the video information, the audio information and the like, the lowest reading rate information recorded for each reproduction unit is reproduced. Then, the record information in each reproduction unit is reproduced by reading the record information at a reading linear velocity not less than a reading linear velocity able to obtain the minimum requirement of the reading rate indicated by the reproduced lowest reading rate information. Therefore, it is possible to perform the reproducing operation satisfactorily while restraining the electric power consumption to be a relatively low level by restraining the operation amount of the reproducing apparatus such as the rotation of the spindle motor and the like, according to this lowest reading rate information by the reproducing apparatus.
In one aspect of the information reproducing apparatus of the present invention, the control device determines the reading linear velocity for reading the record information on the basis of the reproduced lowest reading rate information, and outputs a drive control signal to the drive device to move the information record medium at the determined reading linear velocity.
According to this aspect, when the lowest reading rate information is reproduced, the reading linear velocity for reading the record information is determined on the basis of this reproduced lowest reading rate information, by the control device. Then, on the basis of the drive control signal outputted from the control device, the information record medium can be moved at this determined reading linear velocity, by the drive device.
In another aspect of the information reproducing apparatus of the present invention, the control device determines the reading linear velocity for reading the record information on the basis of the reproduced lowest reading rate information, and outputs a reproduction control signal to the reproduction device to reproduce the record information read by the read device by use of predetermined parameters for reproduction, which correspond to the determined reading linear velocity.
According to this aspect, when the lowest reading rate information is reproduced, the reading linear velocity for reading the record information is determined on the basis of this reproduced lowest reading rate information, by the control device. Then, on the basis of the reproduction control signal outputted from the control device, the record information read by the read device is reproduced by the reproduction device, by use of predetermined parameters for reproduction, which correspond to this determined reading linear velocity.
In another aspect of the information reproducing apparatus of the present invention, the lowest reading rate information indicates one of a first reading rate and a second reading rate which is equal to the first reading rate multiplied by xc2xdn (n: natural number), and the reproduction device is provided with a PLL (Phase Lock Loop) circuit having a frequency divider for demodulating the record information read by the read device.
According to this aspect, since it is enough to perform the demodulation of the record information in accordance with the reading rate equal to the first reading rate multiplied by xc2xdn (n=1, 2, 3, . . . ), the record information read by the read device can be demodulated by use of a relatively simple construction i.e. a PLL (Phase Lock Loop) circuit having the known frequency divider, so that the reproduction which is harmonized with the information rate and which electric power consumption is low can be performed.
In another aspect of the information reproducing apparatus of the present invention, the reproduction unit is a whole of the information record medium. The lowest reading rate information is recorded at a lead in area of the information record medium. The control device controls the read device, the drive device and the reproduction device to reproduce the lead in area so as to reproduce the lowest reading rate information in advance of reading the record information by the read device, determines the reading linear velocity for reading the record information on the basis of the reproduced lowest reading rate information in the lead in area, and controls the read device, the drive device and the reproduction device to reproduce the record information at the determined reading linear velocity for a whole of the information record medium.
According to this aspect, the lead in area is firstly reproduced. Then, the reading linear velocity is determined on the basis of this reproduced lowest reading rate information, by the control device. Therefore, the reproduction of the whole of-the information record medium can be easily performed by use of this determined reading linear velocity.
In another aspect of the information reproducing apparatus of the present invention, the reproduction unit comprises a plurality of second data groups, each of which is a unit able to be logically divided in the reproduction and comprises sequential first data groups arranged along the record track among the first data groups, the lowest reading rate information is recorded at a predetermined portion on the record track for each of the second data groups, and the control device controls the read device, the drive device and the reproduction device to reproduce the predetermined portion for each of the second data groups in advance of reading the record information by the read device, determines the reading linear velocity for reading the record information for each of the second data groups, on the basis of the reproduced lowest reading rate information for respective one of the second data groups, and controls the read device, the drive device and the reproduction device to reproduce the record information at the determined reading linear velocity for each of the second data groups.
According to this aspect, when each of the second data groups is to be reproduced, the lowest reading rate information corresponding to respective one of the second data groups is firstly reproduced. Then, the reading linear velocity for each of the second data groups is determined on the basis of this reproduced lowest reading rate information, by the control device. Thus, the reproduction of each of the second data groups can be easily performed by use of this determined reading linear velocity. Therefore, in a case where the lowest reading rates are considerably different from each other between the second data groups, by employing the reading linear velocity suitable for each of the second data groups, the electric power consumption can be restrained to be a low level as a whole.
The nature, utility, and further features of this invention will be more clearly apparent from the following detailed description with respect to preferred embodiments of the invention when read in conjunction with the accompanying drawings briefly described below.